foods Review Coffee Brews: Are They a Source of Macroelements in Human Nutrition? Ewa Olechno 1, Anna Pu´scion-Jakubik 2,* , Katarzyna Socha 2 and Małgorzata Elzbieta˙ Zujko 1 1 Department of Food Biotechnology, Faculty of Health Science, Medical University of Białystok, Szpitalna 37 Street, 15-295 Białystok, Poland; [email protected] (E.O.); [email protected] (M.E.Z.) 2 Department of Bromatology, Faculty of Pharmacy with the Division of Laboratory Medicine, Medical University of Białystok, Mickiewicza 2D Street, 15-222 Białystok, Poland; [email protected] * Correspondence: [email protected]; Tel.: +48-8574-854-69 Abstract: Coffee brews, made by pouring water on coffee grounds or brewing in an espresso machine, are among the most popular beverages. The aim of this study was to summarize data on the content of macroelements (sodium, potassium, calcium, magnesium, and phosphorus) in coffee brews prepared with different methods, as well as to review the factors influencing the content of the elements. Studies from 2000 to 2020, published in the PubMed and Google Scholar databases, were reviewed. Taking into account the results presented by the authors, we calculated that one portion of coffee brew can cover 7.5% or 6.4% (for women and men) and 6.6% of the daily requirement for magnesium and potassium, respectively. Coffee provides slightly lower amounts of phosphorus (up to 2.2%), sodium (up to 2.2%), and calcium (up to 0.7% of the daily requirement for women and 0.6% for men). If coffee is drunk in the quantity of three to four cups, it can be an important source of magnesium, considering the risk of magnesium deficiency in modern societies. Citation: Olechno, E.; Pu´scion-Jakubik, A.; Socha, K.; Zujko, M.E. Coffee Keywords: coffee; calcium; magnesium; phosphorus; potassium; sodium Brews: Are They a Source of Macroelements in Human Nutrition? Foods 2021, 10, 1328. https:// doi.org/10.3390/foods10061328 1. Introduction Academic Editors: Cláudia P. Passos Coffee is a widely consumed drink, hence the great interest of researchers in its and Ana S. P. Moreira biochemical composition and effect on health. Coffee consumption is growing year by year. In 2017/2018, it amounted to 9,682,620 tons, while at the turn of 2020/2021, it was Received: 9 May 2021 9,997,680 tons [1]. There are many varieties of coffee, but most commercial coffees are Accepted: 7 June 2021 called Arabica (Coffea arabica L.) or Robusta. Robusta is not even Coffea canephora var. Published: 9 June 2021 robusta, but consists of other varieties [2–4]. The positive effect of coffee on the body has been discussed in several meta-analyses [5–8]. Coffee contains over one thousand bioactive Publisher’s Note: MDPI stays neutral ingredients [9], including: carbohydrates, lipids, proteins, chlorogenic acids, diterpenes, with regard to jurisdictional claims in alkaloids, e.g., trigonelline and caffeine, free amino acids, and minerals [10]. The content of published maps and institutional affil- minerals varies across varieties and brews made using different methods, being lower in iations. brews than in coffee beans [11]. Green coffee beans usually contain 3.0–5.4% of minerals on a dry matter basis [11,12]. On the other hand, roasting does not change the concentration of minerals [13]. The main component of coffee beans is potassium—it constitutes 40% of the ash [11,14]. Copyright: © 2021 by the authors. In terms of their importance to humans, minerals can be divided into macroelements Licensee MDPI, Basel, Switzerland. (macronutrients) and microelements (micronutrients). Elements from both of these groups This article is an open access article are essential for the proper functioning of the human organism and have many important distributed under the terms and functions [15,16]. The demand for these substances varies significantly [17]. Both an excess conditions of the Creative Commons and deficiency of certain elements may cause adverse health effects [15,16]. Macroelements Attribution (CC BY) license (https:// are minerals whose content in the body exceeds 0.01% of body weight, and the demand creativecommons.org/licenses/by/ for them is higher than 100 mg per day. Among them are: potassium, sodium, calcium, 4.0/). Foods 2021, 10, 1328. https://doi.org/10.3390/foods10061328 https://www.mdpi.com/journal/foods Foods 2021, 10, 1328 2 of 26 magnesium, phosphorus, sulfur, and chlorine. Micronutrients are found in human organ- isms in smaller amounts—less than 0.01% of body weight, and the demand for them is also lower—less than 100 mg per day. They include: iron, zinc, selenium, copper, chromium, manganese, cobalt, iodine, fluorine, molybdenum, and others. Among minerals, there are also toxic elements, such as aluminum, arsenic, mercury, lead, or cadmium [18]. These can accumulate in the body and pose a health hazard [19]. It seems that coffee can be a source of minerals in the diet, especially if consumed frequently [20]. Plants absorb nutrients from the soil, and therefore the following factors have a significant impact on the composition of coffee beans: the type of coffee, type of soil, cultivation method (including fertilization), environmental pollution (which finds its way into the soil), and production processes [21–27]. Moreover, it seems that the height above sea level and rainfall may also play a role [28–30]. On the other hand, the content of minerals in a brew is influenced by analogous factors affecting the composition of coffee beans, but also by additional variables: the method of brewing, type of water used, brewing time, the ratio of coffee to water, degree of roasting and grinding of coffee beans, or pressure in the case of methods such as coffee machine or coffee pot [13,20,31,32]. The origin of coffee seems to be the most important factor influencing the mineral composition of beans [24,33–37]. Countries and regions vary as to the mineral composition of the soil. It is related to the naturally occurring components and their proportions, as well as to human influence [11,24,32,34,38]. Moreover, minerals differ significantly in their extraction behavior [36,39], and it still remains unclear whether the source of the identified minerals in the coffee brew is water or the coffee itself. An additional factor is the bioavailability of individual ingredients, i.e., the amount that will actually be used by the body. This is influenced by both physiological and nutritional factors as well as food processing [40]. Coffee is a widely consumed drink, so this publication summarizes research on its mineral content to assess whether it can be considered a source of macroelements in a diet. 2. Materials and Methods The study takes into account research from the years 2000 to 2020. The databases searched were Google Scholar and PubMed. The following terms were entered: ‘coffee’, ‘Arabica’, ‘Robusta’, ‘minerals in coffee brews’, ‘macroelements in coffee brews’, ‘sodium’, ‘potassium’, ‘calcium’, ‘magnesium’, ‘phosphorus’, and ‘coffee origin’. We included publi- cations which contained most of these categories of information: the specific type of coffee, coffee origin, brewing method used by consumers, brewing time, amount of coffee and water, type of water, cup volume, temperature, pressure, type of coffee, time and degree of grinding, and the degree of roasting. The exclusion criterion was the use by the authors of a method of brewing which is not commonly used by consumers. 3. Results and Discussion Tables1 and2 contain the literature data obtained as part of the research review for regular and instant coffee brews, respectively. In order to compare the results by various authors, the method of presenting the content of individual minerals in brews was standardized and recalculated, and then expressed as mg/100 mL. In some cases, the results (marked as ‘*’) were presented as per 100 g to be more comparable. It would be necessary to determine the density of the brews prepared by the authors in the publications where the results were expressed as per 100 g in order to correctly assess the amounts of elements that they provide. Thus, these values were only referred to at the end of each paragraph. When the authors reported the content of macroelements per 100 g of coffee (not infusion), the content was converted into a portion of coffee adopted by the authors, and the final volume was assumed as 100 mL. If the authors did not provide a conversion for daily requirement, we made it independently. Foods 2021, 10, 1328 3 of 26 Table 1. The content of macroelements per 100 mL of coffee brew. Content Cup Temperature Av. ± SD Method of Time Coffee Water Type of Pressure Degree of Methods of Volume of Water Species Type of Coffee Origin References (mg/100 mL Brewing (Min.) (g) (mL) Water (Ba) Roasting Analysis (mL) (◦C) or 100 g) Na HR-CS- 28.97 ± 6.35 Turkish coffee nd 5 65 nd up dw nd nd A R fine ground nd [41] FAAS very fine ~2.78 Pouring water 5 17 250 nd fw nd 92 A R nd ICP-OES [20] ground very fine ~2.75 Coffee machine nd 17 nd 250 fw 9 92 A R nd ICP-OES [20] ground medium 2.60 French press 5 17 300 nd fw 1–2 92 A R nd ICP-OES [20] ground ~2.54 Aeropress 2 18 nd 250 fw 2–4 93 A R coarse ground nd ICP-OES [20] 2.52 * Pouring water nd 6 150 nd nd nd nd A&R R ground nd FAAS [42] medium coarse 2.47 Drip method 2.5 18 300 nd fw nd 92 A R nd ICP-OES [20] ground 0.59 Pouring water 5 6 200 nd nd nd 100 nd nd ground # Ethiopia FAAS [36] ground 0.39 * Coffee machine nd 5 40 nd dw nd nd A&R R Asia (India) HR-CS-AAS [32] (capsules) India, Australia, Tanzania, Peru,